In recent years, electricity storage systems have gathered much attention with regard to batteries as electrochemical devices for small-sized and high energy density applications, for example, information-related apparatus, communication apparatus, i.e., personal computers, video cameras, digital cameras, portable telephones, and smartphones; and electricity storage systems for large-sized and high power applications, for example, electric vehicles, hybrid vehicles, auxiliary power systems for fuel cell vehicles, and electric power storage systems. As one of the candidates of such systems, nonaqueous electrolytic solution batteries have been under active development, such as lithium ion batteries, lithium batteries, and lithium ion capacitors.
In the case of lithium ion batteries, a negative electrode may react with lithium cations or an electrolytic solution solvent when lithium cations are intercalated or occluded in the negative electrode at the initial charge. This may result in formation of a film containing lithium oxide, lithium carbonate, and lithium alkylcarbonate as the main components on the surface of the negative electrode. That film on the surface of the electrode which is called Solid Electrolyte Interface (SEI) may, in nature, have significant impact on battery performance. For example, it may reduce reductive decomposition of a solvent to prevent deterioration of battery performance. Further, a film may also be formed on the surface of a positive electrode due to oxidatively decomposed products. This film is also known to play an important role. For example, oxidative decomposition of a solvent may be prevented to reduce the amount of generated battery gas.
In order to improve battery performance, including durability and output characteristics, it is important to form an SEI having a high ion conductivity, a low electron conductivity, and a prolonged stability. To this end, attempts have been widely made for intentionally forming a good SEI by adding a small amount (usually 0.01 mass % or more and 10 mass % or less) of a compound called an additive to an electrolytic solution.
For example, the following additives are used for forming an effective SEI:vinylene carbonate in Patent Document 1; unsaturated cyclic sulfonic acid ester including 1,3-propene sultone in Patent Document 2; carbon dioxide in Patent Document 3; aromatic compounds including 1,2,3,4-tetrahydronaphthalene in Patent Document 4; nitrogen-containing unsaturated compounds including pyridine in Patent Document 5; lithium bis(oxalato)borate in Patent Document 6; and phosphorus-boron complexes including lithium difluoro(oxalato)borate in Patent Document 7. It is noted that Patent Document 8 discloses a method of manufacturing an ionic complex used as an electrolyte for electrochemical devices. Further, Patent Document 9 discloses a method of manufacturing lithium tris(oxalato)phosphate. Moreover, Patent Document 10 discloses an electrolytic solution which can improve a discharge capacity ratio at −20° C./25° C. Furthermore, Nonpatent Document 1 discloses a method of manufacturing fluoro complexes having silicon or the like in the complex center.    Patent Document 1: Japanese Unexamined Patent Application, Publication No. H08-045545 (Japanese Patent No. 3573521)    Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2002-329528 (Japanese Patent No. 4190162)    Patent Document 3: Japanese Unexamined Patent Application, Publication No. H07-176323    Patent Document 4: Japanese Unexamined Patent Application, Publication No. 2003-007334 (Japanese Patent No. 3417411)    Patent Document 5: Japanese Unexamined Patent Application, Publication No. 2003-115324    Patent Document 6: Japanese Unexamined Patent Application, Publication No. 2007-335143    Patent Document 7: Japanese Unexamined Patent Application, Publication No. 2002-110235 (Japanese Patent No. 3722685)    Patent Document 8: Japanese Unexamined Patent Application, Publication No. 2003-137890 (Japanese Patent No. 3907446)    Patent Document 9: Japanese Unexamined Patent Application (Translation of PCT Application), Publication No. 2003-505464 (Japanese Patent No. 4695802)    Patent Document 10: Japanese Unexamined Patent Application, Publication No. 2011-222193 (Japanese Patent No. 5573313)    Non-Patent Document 1: J. Chem. Soc. (A), 1970, 15, 2569-2574